Re: Generic kernel fails to boot on Alpha bisected to b38d08f3181c
Michael Cree <[email protected]>
| Newsgroups | gmane.linux.kernel,gmane.linux.ports.alpha,gmane.linux.debian.ports.alpha |
|---|---|
| Message-ID | <20181214044733.nr43q4wu22ktasvu@tower> |
On Thu, Dec 13, 2018 at 08:07:24AM -0800, Tejun Heo wrote: > Hello, Michael. > > On Thu, Dec 13, 2018 at 09:26:12PM +1300, Michael Cree wrote: > > A kernel built for generic UP Alpha had been noted to fail to boot > > for quite some time (since the release of 3.18). The kernel either > > locks up before printing any messages to the console or just falls > > back into the SRM with a HALT instruction again before any messages > > are printed to the console. A work around is to either use a kernel > > built for generic SMP or to build a machine specific kernel as these > > boot correctly. > > > > Because there were other compile errors at the time it proved > > difficult to bisect, but we are continuing to get complaints about > > it as it renders the Debian Alpha installer somewhat useless, so I > > returned to trying to find the problem and managed to bisect it to: > > > > commit b38d08f3181c5025a7ce84646494cc4748492a3b > > Author: Tejun Heo <[email protected]> > > Date: Tue Sep 2 14:46:02 2014 -0400 > > > > percpu: restructure locking > > > > Any suggestions as to what might be the problem and a fix? > > So, the only thing I can think of is that it's calling > spin_unlock_irq() while irq handling isn't set up yet. Can you please > try the followings? > > 1. Convert all spin_[un]lock_irq() to > spin_lock_irqsave/unlock_irqrestore(). Yes, that's it. With the attached patch the kernel boots. Cheers Michael.
0001-percpu-convert-spin_lock_irq-to-spin_lock_irqsave.patch
(text/x-diff, 1.5 KB)
From e08cf3c714184d8fe168fffcd7d15732924deb1e Mon Sep 17 00:00:00 2001 From: Michael Cree <[email protected]> Date: Fri, 14 Dec 2018 17:24:31 +1300 Subject: [PATCH] percpu: convert spin_lock_irq to spin_lock_irqsave. Bisection lead to commit b38d08f3181c ("percpu: restructure locking") as being the cause of lockups at initial boot on the kernel built for generic Alpha. On a suggestion by Tejun Heo that: So, the only thing I can think of is that it's calling spin_unlock_irq() while irq handling isn't set up yet. Can you please try the followings? 1. Convert all spin_[un]lock_irq() to spin_lock_irqsave/unlock_irqrestore(). --- mm/percpu-km.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/mm/percpu-km.c b/mm/percpu-km.c index 38de70ab1a0d..0f643dc2dc65 100644 --- a/mm/percpu-km.c +++ b/mm/percpu-km.c @@ -50,6 +50,7 @@ static struct pcpu_chunk *pcpu_create_chunk(gfp_t gfp) const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT; struct pcpu_chunk *chunk; struct page *pages; + unsigned long flags; int i; chunk = pcpu_alloc_chunk(gfp); @@ -68,9 +69,9 @@ static struct pcpu_chunk *pcpu_create_chunk(gfp_t gfp) chunk->data = pages; chunk->base_addr = page_address(pages) - pcpu_group_offsets[0]; - spin_lock_irq(&pcpu_lock); + spin_lock_irqsave(&pcpu_lock, flags); pcpu_chunk_populated(chunk, 0, nr_pages, false); - spin_unlock_irq(&pcpu_lock); + spin_unlock_irqrestore(&pcpu_lock, flags); pcpu_stats_chunk_alloc(); trace_percpu_create_chunk(chunk->base_addr); -- 2.11.0